关键词: 高空大气温度, 变化趋势, 突变分析, 新疆地区

Abstract:

With the growing effect of global warming on the environment and socio-economic development, climate change research has become a hot topic and attracted broad attention from national government departments and the public. In its latest report for 2013, the IPCC has noted that the global mean surface temperature has increased by 0.85℃ (0.65-1.06℃), and the annual average temperature from 2003 to 2012 increased by 0.78℃ relative to 1850-1900, a period of nearly 130 years (in 1880-2012), indicating that rapid global warming is an indisputable fact. However, temperature changes are not limited to the earth surface, but are extending to the troposphere and the stratosphere which are important components of the Earth's climate system. Changes occurring at the surface, in the troposphere, and in the stratosphere are three main components of climate change. As an indispensable foundation for climate-change research, the determination on the change trend of upper-air temperature has quickly become one of the most important directions of climate-change research in recent years. In this study, based on the daily observed data from eight sounding stations in Xinjiang in 1980-2013, the change trends, abrupt change points, and their significance of upper-air temperature were analyzed using Mann-Kendall (MK) nonparametric test, and the relation between upper-air and surface temperature changes were also carried on a preliminary discussion. The results are indicated as follows: in last more than 30 years, patterns of statistically significant upper tropospheric and mid-lower stratospheric cooling and mid-lower tropospheric warming are clearly evident. The cooling rate in the upper troposphere and the mid-lower stratosphere was much more intensive than the warming rate in the mid-lower troposphere; Annual temperature cycle suggests that the peak temperature shifts from July in the troposphere to February in the mid-lower stratosphere, indicating the necessity of seasonal trend analysis. There were apparent seasonal differences in the upper-air temperature change, the cooling in the upper troposphere and mid-lower stratosphere in autumn and winter were larger than that in spring and summer, whereas the warming in the mid-lower troposphere was more pronounced during the spring and summer; Abrupt change points of upper-air temperature at three layers all occurred around the early 1990s, which were later than that of the hemisphere temperature, but earlier than that of the corresponding surface temperature; Surface temperature exhibited a significant correlation with mid-lower troposphere temperature, but a remarkable negative correlation with upper troposphere, the mid-lower stratosphere temperatures. Overall, the correlation between surface and mid-lower troposphere temperatures was the highest, followed by the mid-lower stratosphere and upper troposphere temperatures. Temperature changes of mid-lower troposphere and surface exhibited some differences in different periods and seasons, both of them presented warming trends during 1980-2013, while showed cooling trends during 1998-2013. Furthermore, the downward trend during 1998-2013 was more obvious in winter, which suggested that the winter cooling held a dominant position in the temperature descending of the mid-lower troposphere and surface in the last more than 10 years.

Key words: upper-air temperature, variation trend, abrupt change point analysis, Xinjiang